add<文件上传与下载>

pom.xml

@@ -48,6 +48,20 @@
       <version>0.9.5.5</version> <!-- 最新版本请在 Maven 仓库查看 -->
     </dependency>
 
+    <!-- Commons FileUpload -->
+    <dependency>
+      <groupId>commons-fileupload</groupId>
+      <artifactId>commons-fileupload</artifactId>
+      <version>1.4</version>
+    </dependency>
+
+    <!-- Commons IO -->
+    <dependency>
+      <groupId>commons-io</groupId>
+      <artifactId>commons-io</artifactId>
+      <version>2.11.0</version>
+    </dependency>
+
 
 
     <!-- JSTL -->
@@ -65,6 +79,13 @@
       <scope>provided</scope>
     </dependency>
 
+    <dependency>
+      <groupId>com.google.code.gson</groupId>
+      <artifactId>gson</artifactId>
+      <version>2.10.1</version>
+    </dependency>
+
+
     <!-- JSP Implementation (optional, usually provided by your server) -->
     <dependency>
       <groupId>org.apache.tomcat</groupId>

readme.md

@@ -1,6 +1,8 @@
-# jsp+servlet
+# 改进版
+
+- 登录验证码
+- 图片上传下载
 
-## 全局过滤器的应用（鉴权，异常统一处理）
 
 
 

src/main/java/example/controller/CaptchaServlet.java

@@ -0,0 +1,64 @@
+package example.controller;
+
+import javax.servlet.ServletException;
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.Random;
+
+@WebServlet("/captcha")
+public class CaptchaServlet extends HttpServlet {
+
+    // 处理生成验证码图片的请求
+    @Override
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        // 设置响应类型为图片
+        response.setContentType("image/jpeg");
+
+        // 设置验证码内容
+        String captchaText = generateCaptchaText();
+
+        // 将验证码存储到 session 中
+        request.getSession().setAttribute("captcha", captchaText);
+
+        // 创建验证码图片
+        BufferedImage image = new BufferedImage(100, 40, BufferedImage.TYPE_INT_RGB);
+        Graphics2D graphics = image.createGraphics();
+        graphics.setColor(Color.WHITE);
+        graphics.fillRect(0, 0, 100, 40);
+        graphics.setFont(new Font("Arial", Font.BOLD, 30));
+        graphics.setColor(Color.BLACK);
+        graphics.drawString(captchaText, 10, 30);
+
+        // 输出验证码图片
+        OutputStream out = response.getOutputStream();
+        javax.imageio.ImageIO.write(image, "JPEG", out);
+        out.close();
+    }
+
+    // 生成随机的验证码文本
+    private String generateCaptchaText() {
+        String characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
+        StringBuilder captcha = new StringBuilder();
+        Random random = new Random();
+        for (int i = 0; i < 4; i++) {
+            int index = random.nextInt(characters.length());
+            captcha.append(characters.charAt(index));
+        }
+        return captcha.toString();
+    }
+
+    // 检查用户提交的验证码是否正确（忽略大小写）
+    public static boolean validateCaptcha(HttpServletRequest request, String userInputCaptcha) {
+        String sessionCaptcha = (String) request.getSession().getAttribute("captcha");
+        if (sessionCaptcha == null) {
+            return false; // 验证码已过期或不存在
+        }
+        return sessionCaptcha.equalsIgnoreCase(userInputCaptcha);
+    }
+}

src/main/java/example/controller/FileDownloadServlet.java

@@ -0,0 +1,57 @@
+package example.controller;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import javax.servlet.ServletException;
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+@WebServlet("/download")
+public class FileDownloadServlet extends HttpServlet {
+    private static final long serialVersionUID = 1L;
+
+    // 设置文件上传路径（webapp/uploads）
+    private static final String UPLOAD_DIRECTORY = "uploads";
+
+    protected void doGet(HttpServletRequest request, HttpServletResponse response)
+            throws ServletException, IOException {
+
+        // 动态解析 webapp/uploads 的路径
+        String uploadPath = getServletContext().getRealPath("/") + UPLOAD_DIRECTORY;
+
+        // 获取请求的文件名
+        String fileName = request.getParameter("file");
+        if (fileName == null || fileName.isEmpty()) {
+            response.getWriter().println("File parameter is missing");
+            return;
+        }
+
+        // 构造文件的完整路径
+        File file = new File(uploadPath + File.separator + fileName);
+
+        // 检查文件是否存在
+        if (!file.exists()) {
+            response.getWriter().println("File not found: " + fileName);
+            return;
+        }
+
+        // 设置响应的内容类型
+        response.setContentType(getServletContext().getMimeType(file.getName()));
+        response.setContentLength((int) file.length());
+        response.setHeader("Content-Disposition", "inline; filename=\"" + fileName + "\"");
+
+        // 读取文件并写入到响应输出流
+        try (FileInputStream fis = new FileInputStream(file);
+             OutputStream os = response.getOutputStream()) {
+            byte[] buffer = new byte[4096];
+            int bytesRead;
+            while ((bytesRead = fis.read(buffer)) != -1) {
+                os.write(buffer, 0, bytesRead);
+            }
+        }
+    }
+}

src/main/java/example/controller/LoginServlet.java

@@ -1,5 +1,6 @@
 package example.controller;
 
+import example.model.Result;
 import example.model.User;
 import example.service.IUserService;
 import example.service.impl.UserServiceImpl;
@@ -18,21 +19,29 @@ public class LoginServlet extends HttpServlet {
 
     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
-        resp.setContentType("text/html;charset=utf-8");
+        resp.setContentType("application/json;charset=utf-8");
         req.setCharacterEncoding("utf-8");
+
         String username = req.getParameter("username");
         String password = req.getParameter("password");
+        String captcha = req.getParameter("captcha");
+
         try {
+            if (!captcha.equalsIgnoreCase((String) req.getSession().getAttribute("captcha"))) {
+                resp.getWriter().write(toJson(Result.error("验证码错误")));
+                return;
+            }
+
             User user = userService.login(username, password);
-            if(user!=null){
-                req.getSession().setAttribute("user",user);
-                resp.sendRedirect("/computer?action=list");
-            }else{
-                req.getSession().setAttribute("msg","用户名或密码错误");
-                resp.sendRedirect("/msg.jsp");
+            if (user != null) {
+                req.getSession().setAttribute("user", user);
+                resp.getWriter().write(toJson(Result.success("登录成功")));
+            } else {
+                resp.getWriter().write(toJson(Result.error("用户名或密码错误")));
             }
         } catch (Exception e) {
-            throw new RuntimeException(e);
+            e.printStackTrace();
+            resp.getWriter().write(toJson(Result.error("系统错误，请稍后重试")));
         }
     }
 
@@ -40,4 +49,10 @@ public class LoginServlet extends HttpServlet {
     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         resp.sendRedirect("/login.jsp");
     }
+
+    private String toJson(Object object) {
+        // 使用简单的 JSON 序列化方式，实际可以使用 Jackson 或 Gson 库
+        return new com.google.gson.Gson().toJson(object);
+    }
 }
+

src/main/java/example/controller/UploadServlet.java

@@ -0,0 +1,83 @@
+package example.controller;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.List;
+import javax.servlet.ServletException;
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.commons.fileupload.FileItem;
+import org.apache.commons.fileupload.disk.DiskFileItemFactory;
+import org.apache.commons.fileupload.servlet.ServletFileUpload;
+
+@WebServlet("/UploadServlet")
+public class UploadServlet extends HttpServlet {
+    private static final long serialVersionUID = 1L;
+
+    // 设置上传目录
+    private static final String UPLOAD_DIRECTORY = "uploads";
+
+    // 上传配置
+    private static final int MEMORY_THRESHOLD = 1024 * 1024 * 3; // 3MB
+    private static final int MAX_FILE_SIZE = 1024 * 1024 * 40;   // 40MB
+    private static final int MAX_REQUEST_SIZE = 1024 * 1024 * 50; // 50MB
+
+    protected void doPost(HttpServletRequest request, HttpServletResponse response)
+            throws ServletException, IOException {
+
+        // 检查请求是否为多部分内容
+        if (!ServletFileUpload.isMultipartContent(request)) {
+            response.getWriter().println("Error: Form must have enctype=multipart/form-data.");
+            return;
+        }
+
+        // 配置上传参数
+        DiskFileItemFactory factory = new DiskFileItemFactory();
+        factory.setSizeThreshold(MEMORY_THRESHOLD);
+        factory.setRepository(new File(System.getProperty("java.io.tmpdir")));
+
+        ServletFileUpload upload = new ServletFileUpload(factory);
+        upload.setFileSizeMax(MAX_FILE_SIZE);
+        upload.setSizeMax(MAX_REQUEST_SIZE);
+
+        // 构造上传路径
+        String uploadPath = getServletContext().getRealPath("") + File.separator + UPLOAD_DIRECTORY;
+
+        // 如果目录不存在，则创建
+        File uploadDir = new File(uploadPath);
+        if (!uploadDir.exists()) {
+            uploadDir.mkdir();
+        }
+
+        try {
+            // 解析请求的内容
+            @SuppressWarnings("unchecked")
+            List<FileItem> formItems = upload.parseRequest(request);
+
+            if (formItems != null && formItems.size() > 0) {
+                for (FileItem item : formItems) {
+                    // 处理非表单字段
+                    if (!item.isFormField()) {
+                        String fileName = new File(item.getName()).getName();
+                        String filePath = uploadPath + File.separator + fileName;
+                        File storeFile = new File(filePath);
+
+                        // 保存文件到磁盘
+                        item.write(storeFile);
+
+                        request.setAttribute("message", "文件上传成功: " + fileName);
+                        request.setAttribute("fileName",fileName);
+                    }
+                }
+            }
+        } catch (Exception ex) {
+            request.setAttribute("message", "错误信息: " + ex.getMessage());
+        }
+
+        // 转发到 JSP 显示消息
+        getServletContext().getRequestDispatcher("/msg.jsp").forward(request, response);
+    }
+}

src/main/java/example/model/Result.java

@@ -0,0 +1,41 @@
+package example.model;
+
+public class Result<T> {
+    private String status; // "success" 或 "error"
+    private String message; // 消息内容
+    private T data; // 附加数据
+
+    public Result(String status, String message, T data) {
+        this.status = status;
+        this.message = message;
+        this.data = data;
+    }
+
+    public Result(String status, String message) {
+        this(status, message, null);
+    }
+
+    public String getStatus() {
+        return status;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public T getData() {
+        return data;
+    }
+
+    public static <T> Result<T> success(String message, T data) {
+        return new Result<>("success", message, data);
+    }
+
+    public static <T> Result<T> success(String message) {
+        return success(message, null);
+    }
+
+    public static <T> Result<T> error(String message) {
+        return new Result<>("error", message, null);
+    }
+}

src/main/webapp/index.jsp

@@ -28,6 +28,13 @@
         </c:if>
     </div>
 
+    <form action="UploadServlet" method="post" enctype="multipart/form-data">
+        <label for="file">选择图片:</label>
+        <input type="file" name="file" id="file" required>
+        <button type="submit">上传</button>
+    </form>
+
+
 
 </body>
 </html>

src/main/webapp/login.jsp

@@ -1,23 +1,61 @@
 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
-    <!DOCTYPE html>
-    <html>
+<!DOCTYPE html>
+<html>
 
-    <head>
-        <script src="https://www.liyansheng.top/cdn/watermark.js"></script>
-    </head>
+<head>
+    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
+    <script>
+        $(document).ready(function () {
+            // 绑定表单提交事件
+            $('#loginForm').submit(function (event) {
+                event.preventDefault(); // 阻止表单默认提交行为
 
-    <body>
-        <h2>-电脑商城-用户登录</h2>
-        <form action="login" method="post">
-            <label for="username">用户名:</label>
-            <input type="text" id="username" name="username" required><br><br>
-            <label for="password">密码:</label>
-            <input type="password" id="password" name="password" required><br><br>
-            <button type="submit">登录</button>
-            <a href="/register">没有账号?去注册</a>
-        </form>
-        <br>
-        ${requestScope.msg}
-    </body>
+                // 获取表单数据
+                const formData = $(this).serialize();
 
-    </html>
+                // 异步请求
+                $.ajax({
+                    url: '/login',
+                    type: 'POST',
+                    data: formData,
+                    dataType: 'json',
+                    success: function (response) {
+                        if (response.status === 'success') {
+                            alert(response.message);
+                            window.location.href = '/computer?action=list'; // 跳转至主页
+                        } else {
+                            $('#message').text(response.message).css('color', 'red');
+                        }
+                    },
+                    error: function () {
+                        $('#message').text('请求失败，请稍后重试').css('color', 'red');
+                    }
+                });
+            });
+
+            // 刷新验证码
+            $('#captchaImage').click(function () {
+                $(this).attr('src', '/captcha?timestamp=' + new Date().getTime());
+            });
+        });
+    </script>
+</head>
+
+<body>
+    <h2>-电脑商城-用户登录</h2>
+    <form id="loginForm">
+        <label for="username">用户名:</label>
+        <input type="text" id="username" name="username" required><br><br>
+        <label for="password">密码:</label>
+        <input type="password" id="password" name="password" required><br><br>
+        <label for="captcha">验证码</label>
+        <input type="text" id="captcha" name="captcha" required>
+        <img id="captchaImage" src="/captcha" alt="验证码" style="cursor: pointer;" title="点击刷新验证码"><br><br>
+        <button type="submit">登录</button>
+        <a href="/register">没有账号?去注册</a>
+    </form>
+    <br>
+    <p id="message"></p>
+</body>
+
+</html>

src/main/webapp/msg.jsp

@@ -9,6 +9,11 @@
     <body>
         <h2>提示:</h2>
         <h3>${sessionScope.msg}</h3>
+        <h3>${message}</h3>
+            <!-- 动态生成图片标签 -->
+            <c:if test="${not empty fileName}">
+                <img src="/download?file=/${fileName}" alt="Uploaded Image" style="max-width: 100%; height: auto;">
+            </c:if>
         <button onclick="window.history.back();">返回</button>
 
     </body>